Improvement in key-hole guards



s. La. BLANc s@ X. SLPIERRE,

KEY-HOLE GUARD.

Patented May'30,18'76.

UNirrnn STATES PATENT OFFIon.7

J OEIN LA BLANC AND XAVIER ST. PIERRE,- OF SAN FRANCISCO, CAL.-

IMPROVEMENT IN KEY-HOLE GUARDS.

Specification forming'part of Letters Patent No. 178,065, dated May 30, 1876; application filed Apru 4, 1876.

- of a lock, with our improved key-hole guard.

Similar letters of reference indicate corresponding parts. l

Theinvention relates to au improved keyhole gu rd for locks that close the key-hole securely against the introduction of keys or tools from the outside; and the invention consists of a sliding guard-plate operated by a crank-pin sliding' in a segmental recess of the faceplate-of the lock, and in a slot of the guard-plate, as hereinafter more fully described, and definitely' claimed. l

In the drawing, A represents a door-lock of any suitable construction, whiehis provided at the outside faceplate near the keyhole, with a guard-plate, B, sliding in a guide-cas- A ing, B', of the face-plate. The guard-plate B is carried forward and backward, so as to close or open the key-hole by a crank-pin, C, that passes through a segmental slot, a, of the face-plate into a straight slot, b, at the rear end of the guard-plate. The crank-pin C is turned by means of a shaft, D, with thumbpiece applied to the crank, and passing through the inner face-plate to the inside of the room, the segmental slot being preferably made length to correspond with the segmental slot n to admit the free motion of the crank-pin in opening and closing theguard-plate. The guard-plate cannot be forced back from the ,outside, and etfectually closes the keyhole,

so as to preventany tampering with the lock by skeleton keys, tools, 8vo., from the outside.

The shaft and thumb-piece may be made detachable by being' litted into a socket of the crank, and held in place by means of a rose screwed to the door. The shank of the thumb-piece screws into the rose to be retained thereby, until the saine is unscrewed. This admits the application ofthe lock to any thickness of door.

Having thus described our'invention, We claim as new and desire to secure by Letters Patent- The combination of the outervface-plate of a door-look, having' a segmentalreeess, a, With a sliding andguided key-hole guard, B, having a straigl1t slot, b, and with a crank-pin, C, and shaft D turned from the inside of the lock, substantially as speeied.

JOHN LA BLANC.

XAVIER ST. PIERRE. Witnesses: s

WILLIAM HRNEY, FRANK J. SKELLY. 

